Nuka Godfredsen's impression of 'Inuk', a 4000-year-old man from Greenland whose genome has been sequenced.

He had brown eyes, dark skin, thick blackish hair and type A blood. This Eskimo, who lived about 4000 years ago in Greenland, also had dry earwax, an increased risk of going bald and the metabolism of a person who could survive in a cold climate.

And his ancestors were, to the surprise of scientists, ancient people in east Siberia rather than neighbouring Native Americans or Inuit.

All this detailed information about the long-dead man comes from a study of a clump of his hair, which was preserved for thousands of years in the Arctic permafrost. Given the name Inuk, he will go down in history as the first ancient person to have had his full DNA code, or genome, sequenced.

Inuk, who was also inbred, is thought to have belonged to the extinct Saqqaq culture, the first group of people known to have settled in Greenland.

A team led by Eske Willerslev of the University of Copenhagen sequenced the DNA preserved in his frozen hair and compared it with the DNA of modern humans. The results are published in the journal Nature.

The team looked at more than 350,000 tiny differences in the DNA code which are associated with characteristics such as physical appearance and ancestry.

Inuk's ancestry suggests that a previously unknown human migration occurred about 5500 years ago. It appears a large group of his ancestors from eastern Siberia crossed the Bering Strait and travelled through North America to Greenland.

The researchers said the next technical challenge would be to try to sequence ancient DNA from human remains found outside the permafrost region.